Underwater transducer



Oct. 3, 1967 A. NELKIN ETAL 3,345,607

UNDERWATER TRANSDUCER Filed Sept. 24, 1965 U) 3 9 sz 50 Axes j FIG.2. 40 so WITNESSES INVENTORS 2 Arthur Nelkin, John H.Thomoson and Frederick GBGeil li w W/w W United States Patent Vania Filed Sept. 24, 1965, Ser. No. 489,971 2 Claims. (Cl. 340-8) This invention relates to transducers for producing sound waves, and more particularly to transducers which are particularly adapted for operation beneath the surface of water.

Transducers have been adapted to generate sound waves within an aqueous medium. Typically, such devices have involved a means for producing mechanical vibration such as a voice and linking means for transmitting the vibration to a special diaphragm member which is in direct contact with the aqueous solution. Since World War II, the sport of scuba diving has grown in popularity and the number of participants has increased rapidly. In the enjoyment of this sport, there exists a real need for an inexpensive transducer which may be conveniently carried beneath the surface of the water as upon a belt disposed about the waist of the participant. However, the transducers of the prior art have been prohibitively expensive in that they have used special voice coils, and diaphragms which are directly associated with the aqueous medium.

Itis an object of this invention to provide a new and improved transducer device which is particularly adapted for operation beneath the surface of aqueous medium.

Another object of this invention is to provide a new and improved transducer which may be produced with a minimum of expense.

A still further object of this invention is to provide a new and improved underwater transducer which utilizes an inexpensive loudspeaker as the driving means.

Briefly, the present invention accomplishes the above cited objects by providing an improved transducer in which a means for translating an electrical signal into a mechanical vibration is linked to the aqueous medium by a member of a rigid material having a mass per unit volume less than that of the surrounding aqueous medium. Further, the pressure upon both sides of the rigid memher is equalized by the inclusion of a collapsible member associated with the rigid member in an air-tight relation and exposed to the aqueoeus medium for thereby applying pressure to the inserted rigid member. More specifically, the transducer includes an enclosure having a first sealed compartment in which there is disposed an inexpensive loudspeaker having a conventional voice coil and vibrating cone. A portion of the first chamber through which the sound waves are to transmitted is sealed by a flexible member and the rigid member as described above is disposed in a sound transmitting relationship between the sealing member and the cone of the loudspeaker. Further, the transducer may include a second compartment in which there is disposed the collapsible member such as a bladder which is connected as by tubing to the first compartment and is exposed to the aqueous medium which exerts a pressure upon the collapsible member and, in turn, upon the cone of the loudspeaker.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of the specification.

For a better understanding of the invention reference may be had to the accompanying drawings in which:

FIGURE 1 is an isometric view of a transducer assembly embodying the teachings of this invention; and

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FIGURE 2 is a side View of the transducer assembly shown in FIG. 1.

Referring now to the drawings, there is shown a transducer assembly 10 including an enclosure 12 having one end thereof enclosed by an end plate 14 and a flange 16 disposed radially inward upon the other end thereof. A sealing member '18 made of a suitable water impermeable material such as neoprene is secured to the flange 16 as by a sealing composition 20 which is disposed about the periphery of the sealing member 18. The sealing composition 20 is made of a suitable water resistant, adhering material such as a silicon rubber cement.

A loudspeaker or transducer element 22 is disposed against the aperture formed by the flange 16 and is secured thereto by suitable fasteners 34 such as a plurality of nuts and bolts. The transducer element 22 as illustrated in the drawings has a conventional paper cone 23 with a voice cylinder 28 secured thereto. A voice coil (not shown) is inserted into a magnetic gap (not shown) which is part of the magnetic housing 24. The magnetic housing 24 is disposed upon a support member 26 which is in turn connected to an integral flange 30. Holes '32 and 33 are formed respectively in the integral flange 30 and in the flange 16 to provide openings through which the fasteners 34 are inserted. It is noted that speakers known in the art as high frequency speakers or tweeters can be easily incorporated in the assembly 10. In particular, the stiffer cones of such speakers are of advantage in transmitting sound beneath the surface of the Water.

It is an important aspect of this invention that a motion translating means 38 be inserted between the voice cylinder Z8 and the cone 23, and the sealing member 1% in order that the mechanical vibration induced by the loudspeaker or transducer device 22 be efliciently conveyed to the aqueous medium surrounding the assembly 19. Further, the motion translating means 38 should be of a rigid structure in order to convey the mechanical motion and should be of a lower mass per unit volume than that of the surrounding aqueous medium in order that the efliciency of the transducer be as high as possible. If the translating means 38 has a higher density than the surrounding medium, then the transducer 22 would require considerably more power to be operated and the electro-mechanical efficiency of the transducer 22 would be severely reduced. It is noted that many materials which would be suitable for making the means 38 are of a cellular construction and therefore the requirement concerning the mass per unit volume of the means 38 refers to the mass per unit of the entire volume defined by the periphery of the means 38. In an illustrative embodiment as shown in the drawings, the means 38 is of a conical configuration and may be secured to the cone 23 and to the sealing member 18 by an appropriate cement. Further, a suitable material of which to make the means 38 and having the above enumerated properties would be a polystyrene foam.

A cylindrical compartment 40 in which suitable electronic equipment may be disopsed to drive the transducer 22 is inserted within the enclosure 12 so as to form a first, air-tight chamber 42 in which the transducer 22 is mounted. Upon the other side of the cylindrical compartment 40, there is formed a second chamber 52 in which there is disposed a compressible member 46. The compressible member 46 may illustratively be a collapsible bladder made of a material impermeable to both air and water. A tube 44 is disposed within an opening 39 through the cylindrical compartment 40 to form a passageway between the first and second chambers. It is noted that the tube 44 is connected to the compressible member 46 by an air-tight seal 48 so that when pressure is exerted upon the member 46, the medium with the member 46 (typically air) is forced into the first chama or ber 42 to thereby equalize the pressure upon the cone 23. Further a plurality of openings 50 are disposed within the enclosure 12 and the end plate 14 in order to allow the surrounding medium to flow into and to exert a force upon the compressible member 46.

Thus, there has been shown a transducer which is particularly adaptable to be operated beneath the surface of the Water and which utilizes a conventional speaker to efficiently transmit sound waves through the surrounding water. In summary, this is accomplished by the use of a rigid, light weight insert disposed between the vibrating cone of the transducer and the sealing member of the enclosing assembly. Further, a compressible means such as a bladder is disposed in an air-tight relationship with the transducer so as to increase the pressure upon the flexible diaphragm of the transducer in response to the pressure of the ambient aqueous solution upon the bladder.

While there has been shown and described what is at present considered to be the preferred embodiment of this invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

We claim as our invention:

1. A loudspeaker assembly for operation beneath the surface of water comprising an acoustical-electrical transducer element having a flexible diaphragm, an enclosure surrounding said transducer element and sealing said transducer element from said water, said enclosure having an opening therein over which there is disposed a flexible member impervious to water and sealed to said enclosure to resist the ingress of said water, a member having a first surface coupled to said diaphragm for transmitting sound waves from said transducer element to a second surface of said member coupled to said flexible member, said member for transmitting being structurally rigid and having a mass per unit volume less than that of water, and a collapsible bladder connected in an air-tight relationship to said transducer element and in a pressure responsive relationship to said water for maintaining equal pressure on either side of said member for transmitting.

2. A loudspeaker assembly to be operated beneath the surface of water comprising an acoustical-electrical transducer element having a diaphragm, an enclosure completely surrounding said transducer element and sealing said transducer element from the ingress of water, said enclosure having a first opening therein which is covered with a flexible member impervious to water and having a water tight seal with said enclosure, a member disposed having a first surface coupled to said diaphragm for transmitting sound waves to a second surface of said member having a greater area than said first surface, substantially all of said second surface disposed in contact with said flexible member, said transmitting member having a rigid structure and having a mass per unit volume less than that of said ambient water, a compartment for receiving electronic elements to drive said transducer element disposed within said enclosure to form a first, air-tight chamber about said transducer element and a second chamber having at least one opening therein through which said ambient water may flow, and a flexible bladder disposed within said second chamber in an air-tight relationship with said first chamber for maintaining the pressure within said first chamber equal to that of said ambient water.

References Cited UNITED STATES PATENTS 2,297,218 9/1942 Henrich et al. 18132 2,429,104 10/ 1947 Olson. 3,187,832 6/1965 Broadley 181-311 X RODNEY D. BENNETT, Primary Examiner.

CHESTER L. JUSTUS, Examiner.

B. L. RIBANDO, Assistant Examiner. 

1. A LOUDSPEAKER ASSEMBLY FOR OPERATION BENEATH THE SURFACE OF WATER COMPRISING AN ACOUSTICAL-ELECTRICAL TRANSDUCER ELEMENT HAVING A FLEXIBEL DIAPHRAGM, AN ENCLOSURE SURROUNDING SAID TRANDUCER ELEMENT AND SEALING SAID TRANSDUCER ELEMENT FROM SAID WATER, SAID ENCLOSURE HAVING AN OPENING THEREIN OVER WHICH THERE IS DISPOSED A FLEXIBLE MEMBER IMPERVIOUS TO WATER AND SEALED TO SAID ENCLOSURE TO RESIST THE INGRESS OF SAID WATER, A MEMBER HAVING A FIRST SURFACE COUPLED TO SAID DIAPHRAGM FOR TRANSMITTING SOUND WAVES FROM SAID TRANSDUCER ELEMENT TO A SECOND SURFACE OF SAID MEMBER COUPLED TO SAID FLEXIBLE MEMBER, SAID MEMBER FOR TRANSMITTING BEING STRUCTURALLY RIGID AND HAVING A MASS PER UNIT VOLUME LESS THAN THAT OF WATER, AND A COLLAPSIBLE BLADDER CONNECTED IN AN AIR-TIGHT RELATIONSHIP TO SAID TRANSDUCER ELEMENT AND IN A PRESSURE RESPONSIVE RELATIONSHIP TO SAID WATER FOR MAINTAINING EQUAL PRESSURE ON EITHER SIDE OF SAID MEMBER FOR TRANSMITTING. 